Extracts of broccoli and banana may help in fighting stomach problems, research suggests. Laboratory studies show fibres from the vegetables may boost the body's natural defences against stomach infections. Trials are under way to see if they could be used as a medical food for patients with Crohn's disease. Crohn's disease is an inflammatory bowel disease that causes symptoms such as diarrhoea and abdominal pain. It affects about 1 in 1,000 people, and is thought to be caused by a mixture of environmental and genetic factors. The condition is common in developed countries, where diets are often low in fibre and high in processed food.

Scientists at the University of Liverpool looked at how roughage from vegetables influenced the passage of harmful bacteria through cells inside the gut. They found that fibres from the plantain, a type of large banana, and broccoli, were particularly beneficial. But a common stabiliser added to processed foods during the manufacturing process had the opposite effect.

Dr Barry Campbell, from the University of Liverpool, said: “This research shows that different dietary components can have powerful effects on the movement of bacteria through the bowel. “We have known for some time the general health benefits of eating plantain and broccoli, which are both high in vitamins and minerals, but until now we have not understood how they can boost the body's natural defences against infection common in Crohn's patients. “Our work suggests that it might be important for patients with this condition to eat healthily and limit their intake of processed foods.”

The research, published in the journal Gut, and carried out in collaboration with experts in Sweden and Scotland, investigated special cells, called M-cells, which line the gut and ward off invading bacteria. Work was carried out in laboratory-grown cells and tissue samples from patients undergoing surgery for stomach problems. Clinical trials are now underway in 76 Crohn's patients to find out whether a medical food containing plantain fibres could help keep the disease at bay. “It may be that it makes sense for sufferers of Crohn's to take supplements of these fibres to help prevent relapse,” said Professor Jon Rhodes of the University of Liverpool.

Using a UK database of electronic medical records, he and his colleagues identified 367 children and adults diagnosed with Crohn's disease and 591 diagnosed with ulcerative colitis between 2005 and 2008. The researchers matched each of those people to five IBD-free individuals the same age and sex.

They then used air-quality data from government monitors to assess the average yearly levels of three air pollutants in the study subjects' residential areas.

The pollutants included nitrogen dioxide, which is produced largely by vehicles and is highest in urban, high-traffic areas; sulfur dioxide, which is produced through industrial processes, including the burning of coal and oil; and particulate matter, fine particles emitted via car exhaust, as well as power plants and other industrial sources.

Overall, Kaplan's team found no association between IBD and the three air pollutants across the study group as a whole.

However, young people — those age 23 or younger — were about twice as likely to be diagnosed with Crohn's disease if they lived in a region in the top 60 percent of nitrogen dioxide levels, versus the bottom 20 percent.

Similarly, people age 25 or younger were twice as likely to have ulcerative colitis if they lived in areas with higher sulfur dioxide levels. However, there was no evidence of a “dose-response” relationship — that is, the risk of ulcerative colitis climbing steadily as sulfur dioxide levels rose.

That lack of a dose-response, Kaplan told Reuters Health, “makes us a little more cautious about that finding.”

Indeed, he urged caution in interpreting the findings as a whole. While he and his colleagues tried to account for other factors — such as study subjects' smoking habits and socioeconomic status — they cannot rule out the possibility that something other than air pollution itself accounts for their findings.

“This is an interesting association,” Kaplan said. But, he added, the findings do not prove cause-and-effect.

As for why air pollution would affect IBD risk, Kaplan said he could only speculate, based on research into other health conditions, including heart and lung disease. Studies indicate that air pollutants can trigger inflammation in the body; that, Kaplan explained, raises the possibility that in genetically predisposed people, air pollution may trigger an inflammatory response in the intestines that leads to IBD.

Since the current study found a relationship between pollutants and IBD only in young people, the findings also raise the question of whether children and teenagers are particularly susceptible to any effects of air pollution on the risk of the digestive disorders.

Much more research is needed, Kaplan said — both larger population studies and research in animals to see how exposure to various air pollutants might affect intestinal health.

He added that no one is proposing that air pollution is the environmental cause of IBD; if it does turn out to be a factor, he said, it will likely be one of many players.

But if air pollution is confirmed as a risk factor, there would be important implications, Kaplan said, since air quality is something that can be modified.

People who take aspirin regularly for a year or more may be at an increased risk of developing Crohn's disease, according to a new study by the University of East Anglia (UEA). Led by Dr Andrew Hart of UEA's School of Medicine, the research was presented for the first time at the Digestive Disease Week conference in New Orleans.

Crohn's disease is a serious condition affecting 60,000 people in the UK and 500,000 people in the US. It is characterized by inflammation and swelling of any part of the digestive system. This can lead to debilitating symptoms and requires patients to take life-long medication. Some patients need surgery and some sufferers have an increased risk of bowel cancer.

Though there are likely to be many causes of the disease, previous work on tissue samples has shown that aspirin can have a harmful effect on the bowel. To investigate this potential link further, the UEA team followed 200,000 volunteers aged 30-74 in the UK, Sweden, Denmark, Germany and Italy. The volunteers had been recruited for the EPIC study (European Prospective Investigation into Cancer and Nutrition) between 1993 and 1997.

The volunteers were all initially well, but by 2004 a small number had developed Crohn's disease. When looking for differences in aspirin use between those who did and did not develop the disease, the researchers discovered that those taking aspirin regularly for a year or more were around five times more likely to develop Crohn's disease.

The study also showed that aspirin use had no effect on the risk of developing ulcerative colitis — a condition similar to Crohn's disease.

“This is early work but our findings do suggest that the regular use of aspirin could be one of many factors which influences the development of this distressing disease in some patients,” said Dr Hart.

“Aspirin does have many beneficial effects, however, including helping to prevent heart attacks and strokes. I would urge aspirin users to continue taking this medication since the risk of aspirin users possibly developing Crohn's disease remains very low — only one in every 2000 users, and the link is not yet finally proved.”

Further work must now be done in other populations to establish whether there is a definite link and to check that aspirin use is not just a marker of another risk factor which is the real cause of Crohn's disease. The UEA team will also continue its wider research into other potential factors in the development of Crohn's disease, including diet.